What Are Antimicrobial Coatings?

Antimicrobial coatings are coatings that are treated with an antimicrobial agent and applied to a surface to prevent the growth of bacteria, mold, mildew, or algae.

PVC, latex, polyurethane, ink, paint, lacquer, powder coatings, etc. are coated onto hard surfaces or textiles to create goods with new properties or features. Regardless of their nature, most coatings are susceptible to bacterial, fungal, and/or algal growth.

Bacterial and fungal growth affects these coatings by producing bacterial or musty fungal odors, staining, and/or loss of inherent properties. This leads to a reduced lifespan of the product. Antimicrobial coatings add value and functionality to finished products by reducing odors, staining, and by extending product life.

What is an antimicrobial agent? We've got you covered.

Benefits of Antimicrobial Additives for Coatings?

An antimicrobial coating offers proven surface protection by controlling the growth of unwanted bacteria and fungi. An antimicrobial coating for plastic, for example, can enhance surfaces in healthcare institutions, catering facilities, washrooms, and more by minimizing the presence of bacteria that cause odor generation and product degradation.

Antimicrobial additives for coatings can also offer protection against fungi, mold, and mildew, a key feature, particularly for outdoor applications. An antimicrobial coating for plastic is especially beneficial. It helps prolong the life of plastic materials by preventing discoloration, loss of tensile strength, and cracking that often occurs through fungal growth.

Active Ingredients Used to Make Antimicrobial Coatings

The most common actives used to manufacture antimicrobial coatings include various isothiazolinone treatments, zinc pyrithione, silver, and quaternary ammonium compounds. Each active ingredient has its strengths and weaknesses.

For example; zinc, silver, and quats have strong efficacy against bacteria but their fungal efficacy is either non-existent, or high levels of the antimicrobial additive are required. Likewise, isothiazolinones have robust fungal efficacy but are less effective against bacteria or require more of the active to work effectively.

Synergistic combinations of different actives can lower overall anti-microbial use levels, provide economical savings, and most importantly, deliver superior antimicrobial performance.

By creating unique combinations of antimicrobial actives, the Ultra-Fresh suite of antimicrobial additives for coatings offer something different compared to off-the-shelf products sold by larger antimicrobial coating companies.

Ultra-Fresh antimicrobial additives are highly effective at lower use levels. Since less product is required to achieve better efficacy, the manufacturer’s overall costs are lowered.

Need assistance in choosing which antimicrobial additives for coatings are best? We can help! Contact us for more info.

How is an Antimicrobial Coating Made?

Simple to use, an antimicrobial treatment can be added to the liquid stage prior to coating. In most cases, antimicrobial additives can also offer excellent in-can protection prior to use.

Several Ultra-Fresh treatment options for antimicrobial coatings are available. This selection ensures that an ideal product can be found for each end-use and performance requirement.

How are Antimicrobial Coatings Tested?

Many test methods developed by organizations such as the American Association of Textile Chemists and Colorists (AATCC); American Society for Testing and Materials (ASTM); International Organization for Standardization (ISO); and Japanese Industrial Standard (JIS) are available to evaluate the antimicrobial performance of antimicrobial coatings.

Such standardized test methods are often developed for specific types of materials, end-uses, or antimicrobial technologies; therefore, choosing the correct test method is crucial.

Manufacturers looking to assess the bacterial efficacy properties of their anti bacterial coating should use the ISO 22196 (JIS Z 2801).

To test the fungal efficacy of coatings against mold and mildew, standardized test methods such as the AATCC Method 30, Part III, or the ASTM G21 are recommended.

Interested in finding out the difference between antibacterial vs antimicrobial? We've got the answer for you.

Effectiveness of Antimicrobial Coatings

The photos below exemplify the benefit of antimicrobial additives for coatings. Under the right conditions, mold and mildew can flourish by breaking down coatings to use as a food source, especially when moisture is present. An antimicrobial surface coating prevents degradation and deterioration by providing antimicrobial protection.

The wood samples below, both with clear coatings applied, were tested using the AATCC Method 30, Part III. The test organism used was Aspergillus niger.

The sample with an untreated coating supports fungal growth. Over time this causes micro-cracks in the coating, leaving the wood exposed and prone to the effects of moisture, causing further staining and degradation. The antimicrobial coating resists fungal growth, remaining strong and protected.

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Antimicrobial coatings resist fungal attack

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Wood without antimicrobial coatings support fungal growth

Efficacy of Antibacterial Coatings

The photos below demonstrate the effectiveness of an antibacterial coating.

Two coated surfaces, one "as is" (without an antibacterial additive for coatings) and the other with an antimicrobial surface coating, were tested using the ISO 22196.

The same number of bacteria (E. coli) were added to each sample and then incubated at 37C/98F (body temperature) for 24 hours.

Afterward, both surfaces were assessed to determine how many bacteria were remaining after the incubation period.

As seen in the below photo, high numbers of bacteria were recovered from the untreated surface coating. In contrast, hardly any bacteria were recovered from the surface coated with an antibacterial coating.

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Surface coating with Ultra-Fresh antibacterial additive

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Surface without an antibacterial coating

The graph below is another way of demonstrating how antibacterial coatings perform over time. The same number of bacteria were added to a surface with an antibacterial coating and a surface with an untreated coating.

The samples were incubated for 24 hours at 98F/37C (body temperature). Afterward, the number of bacteria remaining on each surface was determined.

The bacteria on the untreated coated surface grew exponentially (from about 50,000 to over 500,000!).

However, the surface with the Ultra-Fresh antibacterial coating had 99.9% fewer bacteria as compared to the surface with the untreated coating after the same time period!*

*Subject to the performance properties of the specific active ingredient manufactured into your product. Treated product efficacy claims against specific microbes are dependant on the results of laboratory testing.

Want to learn more about how antimicrobial coated surfaces work?

Where are Antimicrobial Coatings Used?

Grand View Research estimates the global antimicrobial coatings market size was valued at USD 2.44 billion in 2015 and steady growth is predicted through till 2025. Increasing concerns regarding cleanliness in various industries are contributing to the expanded use of antimicrobial coatings. They are used in a variety of consumer and industrial applications that include:

• Housewares
• Commercial
• Industrial
• Outdoor
• Building Products
• Healthcare

Treatment options are available for virtually all end uses. For more information on which Ultra-Fresh products are suitable for antimicrobial coatings, contact us!

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Interested in learning more about our other antimicrobial applications:

• Antimicrobial fabric treatment
• Antimicrobial plastic and polymers
• Antimicrobial polyurethane foam
• Antimicrobial flooring and carpet